In a manufacturing process of a semiconductor device or a flat panel display (FPD), a cleaning process is performed to remove particles or contaminants adhering to a substrate such as a semiconductor wafer or a glass substrate. As a liquid processing apparatus for performing the cleaning process, there is known a single-wafer processing apparatus configured to hold and rotate a substrate such as a semiconductor wafer on a spin chuck and process the substrate by supplying a processing solution to the substrate.
There has been proposed a method of using an inert gas nozzle for supplying an inert gas to the substrate as well as using a pure water nozzle for supplying pure water (see, Patent Document 1).
Patent Document 1: Japanese Patent Laid-open Publication No. 2001-53051
In the disclosure of Patent Document 1, while supplying the pure water to a surface of the substrate from the pure water nozzle and jetting the inert gas to the surface of the surface from the inert gas nozzle located closer to a center of the substrate than the pure water nozzle, the pure water nozzle and the inert gas nozzle are moved toward a periphery of the substrate from a central portion thereof. Accordingly, a pure water film formed on the surface of the substrate by the rotation of the substrate after the pure water supplied from the pure water nozzle is expelled by the inert gas jetted from the inert gas nozzle. Accordingly, a dry region is expanded from the central portion of the substrate toward the periphery thereof in a substantially concentric shape.
When the pure water film is expanded in an annular shape, however, if minute water drops remain on the surface of the substrate, the remaining minute water drops may not be removed by the inert gas but may be dried. In such a case, it becomes difficult to reduce generation of water marks sufficiently. Since patterns formed on the substrate are miniaturized as semiconductor integrated circuits are highly integrated, generation of these water marks is deemed to be a problem.